NH3 Sensor Based on ZIF-8/CNT Operating at Room Temperature with Immunity to Humidity
Wenjun Yan, Shiyu Zhou, Min Ling, Xinsheng Peng, Houpan Zhou
Abstract
Humidity effects on resistive gas sensors operating at room temperature remain a serious bottleneck. In this work, we introduce a resistive gas sensor based on a zeolitic imidazolate framework-8/carbon nanotube (ZIF-8/CNT) composite for the detection of ammonia gas at room temperature. The composite was prepared using a facile solution method. In this sensor, the basic mechanism was the charge transfer between ammonia molecules and CNTs; meanwhile, the ZIF-8 facilitated the adsorption of ammonia molecules as a preconcentrator, and prevented the adsorption of H2O molecules due to its hydrophobicity; CNTs were threaded through the ZIF-8 to form a great conductive network for charge transfer. The obtained sensor showed good ammonia sensing, especially at room temperature, with great selectivity and immunity to humidity under moderately humid conditions (45–70 % RH). However, the ammonia response was reduced at very high humidity (90% RH) due to the competitive adsorption of H2O molecules. This proved that the NH3 sensor based on ZIF-8/CNT could be suitable for practical applications under moderately humid conditions.